Toxic organophosphorous (OP) agents pose a risk in both civilian and military contexts. OP agents include nerve gases (e.g., soman, sarin, tabun, VX), pesticides, and cocaine. These agents are believed to act by irreversibly inhibiting acetylcholinesterase, which can result in broncho-constriction, respiratory failure, and death. The cholinesterase polypeptides acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) have been successfully applied following exposure to these agents, as well as prophylactically (Doctor et al. (2001) Chemical Warfare Agents: Toxicity at low levels, pp 191-214). In particular, human BuChE has been shown to protect against a wide range of agents. Human BuChE can be used prophylactically without additional post-exposure treatment, and it has a long half-life in humans, rodents, and primates (Ostergaard et al. (1988) Acta Anaesth. Scand., 32:266-69; Raveh et al. (1993) Biochem. Pharmacol. 45:2465-74; Raveh et al. (1997) Toxicol. Appl. Pharmacol. 145:43-53; Allon et al. (1998) Toxicol. Sci. 43:121-28). Because the enzyme comes from a human source, the risk of an adverse immune response is minimized.
Previous efforts at purifying cholinesterase enzymes have relied on anion column chromatography from plasma or Cohn Fraction IV paste (see e.g., Grunwald et al. (1997) J. Biochem. Biophys. Methods 34:123-35; Lockridge et al. (2005) J Med Chem Biol Radiol. 3:nihms5095). For large-scale production these methods would require employing cumbersome chromatography column packing procedures and large amounts of buffers.